Overview: Nb₂O₂

Structure info
Layer group	pm11
Layer group number	11
Structure origin	original03-18

Stability
Energy above convex hull [eV/atom]	0.776
Heat of formation [eV/atom]	-1.305
Dynamically stable	Yes

Basic properties
Magnetic	No
Band gap (PBE) [eV]	0.000

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	2.895	-0.000	0.000	Yes
2	-0.000	5.270	0.000	Yes
3	0.000	0.000	17.290	No

Lengths [Å]	2.895	5.270	17.290
Angles [°]	90.000	90.000	90.000

Crystal structure

Symmetries
2D Bravais type	Rectangular (op)
Layer group number	11
Layer group	pm11
Space group number (bulk in AA-stacking)	6
Space group (bulk in AA-stacking)	Pm
Point group	m
Inversion symmetry	No

Structure data
Formula	Nb2O2
Stoichiometry	AB
Number of atoms	4
Unit cell area [Å2]	15.255
Thickness [Å]	2.156

Stability

Convex hull

Nb2O2 (2NbO-2)
Heat of formation [eV/atom]	-1.30
Energy above convex hull [eV/atom]	0.78

Monolayers from C2DB
Nb4O8 (4NbO2-1)	-2.42 eV/atom
Nb2O4 (2NbO2-1)	-2.38 eV/atom
NbO2 (1NbO2-1)	-2.37 eV/atom
NbO2 (1NbO2-2)	-2.35 eV/atom
NbO2 (1NbO2-3)	-2.20 eV/atom
Nb2O6 (2NbO3-1)	-2.07 eV/atom
Nb4O12 (4NbO3-1)	-1.83 eV/atom
Nb2O2 (2NbO-1)	-1.53 eV/atom
Nb2O2, (2NbO-2)	-1.30 eV/atom
Nb2O2 (2NbO-3)	-1.02 eV/atom

Bulk crystals from OQMD123
Nb2O5	-2.77 eV/atom
Nb8O16	-2.64 eV/atom
Nb3O3	-2.08 eV/atom
Nb	0.00 eV/atom
O8	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	91.46	31.82	0.00
yy	32.59	53.45	-0.00
xy	0.00	0.00	22.56

Stiffness tensor eigenvalues
Eigenvalue 0	22.56 N/m
Eigenvalue 1	35.07 N/m
Eigenvalue 2	109.85 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	0.000
Direct band gap (PBE)	0.000
Fermi level wrt. vacuum (PBE)	-4.616

Fermi surface

Electronic properties

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Nb	0.83
1	O	-1.17
2	Nb	1.57
3	O	-1.23

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	39.311
Interband polarizability (y) [Å]	15.588
Interband polarizability (z) [Å]	0.298
Plasma frequency (x) [eV Å0.5]	2.697
Plasma frequency (y) [eV Å0.5]	3.103

Raman spectrum

Mode	Frequency (1/cm)	Degeneracy
Mode 1	0.5	3
Mode 2	84.7	1
Mode 3	147.	1
Mode 4	236.7	1
Mode 5	366.4	1
Mode 6	392.8	1
Mode 7	471.3	1
Mode 8	505.9	1
Mode 9	529.5	1
Mode 10	624.5	1

Miscellaneous

Miscellaneous details
Unique ID	2NbO-2
Number of atoms	4
Number of species	2
Formula	Nb2O2
Reduced formula	NbO
Stoichiometry	AB
Unit cell area [Å2]	15.255
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB/NbO/Nb2O2-d6da6b621fc8
Old uid	Nb2O2-d6da6b621fc8
Space group (bulk in AA-stacking)	Pm
Space group number (bulk in AA-stacking)	6
Point group	m
Inversion symmetry	No
Layer group number	11
Layer group	pm11
2D Bravais type	Rectangular (op)
Thickness [Å]	2.156
Structure origin	original03-18
Band gap (PBE) [eV]	0.000

Miscellaneous details
Direct band gap (PBE) [eV]	0.000
gap_dir_nosoc	0.000
Vacuum level [eV]	3.005
Fermi level wrt. vacuum (PBE) [eV]	-4.616
minhessianeig	-0.000
Dynamically stable	Yes
Interband polarizability (x) [Å]	39.311
Interband polarizability (y) [Å]	15.588
Interband polarizability (z) [Å]	0.298
Plasma frequency (x) [eV Å0.5]	2.697
Plasma frequency (y) [eV Å0.5]	3.103
Energy [eV]	-36.121
Magnetic	No
Spin axis	z
Magnetic anisotropy energy, xz [meV/unit cell]	0.000
Magnetic anisotropy energy, yz [meV/unit cell]	0.000
Energy above convex hull [eV/atom]	0.776
Heat of formation [eV/atom]	-1.305